The invention relates to a device for conveying printed products through a printing-related machine.
It has become known heretofore to use conveyor belts in order to convey sheets through electrographic printing machines. The published German Patent Document DE 40 152 10 A1 discloses a device for transporting sheet materials, wherein the sheets are retained on the surface of a conveyor belt by electrostatic retaining forces. The conveyor belt is positioned over deflecting or idler rollers. One of the deflecting rollers is driven and causes the belt to be advanced by frictional contact on the side thereof directed away from the sheet. Located along the conveying distance are printing devices which successively apply individual colors of a multicolored printed image to a sheet. The length and width of the conveyor belt are adapted to the dimensions of the printing device. In order to produce a five-color printing image, five printing units are arranged in tandem or behind one another in series along the conveyor belt. Printing machines with a great overall length are produced thereby. When printing with one or two colors takes place on such a printing machine, a series of printing units remains unused, while the sheets always run through the entire conveying distance for five-color printing. A conveyor belt which runs over five printing units undergoes considerable stretching, which impedes control and regulation of the sheet transportation.
It is accordingly an object of the invention to provide a device for conveying printed products through a printing-related machine which allows high flexibility when processing print jobs.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a device for conveying printed products through a printing-related machine, comprising at least one endless conveyor belt running over deflecting rollers and having at least one printed product resting thereon during a conveying operation, and a rotating frictional element provided for driving the conveying belt, the frictional element being in contact with the conveyor belt on a side thereof whereon the printed product is transported.
In accordance with another feature of the invention, the conveyor belt is looped about the frictional element at an angle smaller than 180xc2x0.
In accordance with a further feature of the invention, the frictional element is disposed in a vertically running section of the conveyor belt.
In accordance with an added feature of the invention, the conveying device includes another conveyor belt adjacent to the first-mentioned conveyor belt and, for driving both of the mutually adjacent conveyor belts simultaneously, the frictional element is engageable with both of the conveyor belts on the side thereof, respectively, whereon the printed product is transported.
In accordance with an additional feature of the invention, the conveying device includes another conveyor belt, and wherein, for conveying printed products at least approximately horizontally, the conveyor belts are arranged behind one another, the frictional element being provided in a section thereof wherein the conveyor belts, respectively, in relation to a vertical plane of symmetry, are looped about a sub-section of the frictional element and run over deflecting rollers.
In accordance with yet another feature of the invention, the frictional element is a cylindrical drive roller.
In accordance with yet a further feature of the invention, the printing-related machine is a printing machine with a plurality of printing modules arranged in accordance with a unit construction principle, a respective conveyor belt and a respective frictional element being assigned to each of the printing modules, at least one of the frictional elements being driven.
In accordance with a concomitant feature of the invention, the conveying device includes a convexly curved guide over which the conveyor belt runs in a conveying path for printed products.
By providing a rotating frictional element on that side of a conveyor belt whereon the printed products are transported makes it possible, in particular, for printing machines to be assembled from individual modules, the outlay for driving the conveyor belts of the modules being low. The belt lengths in a module are determinable quite well by suitable control technology. When a plurality of modules are provided in series or tandem, a printed product is transferred from module to module. Appropriate transport of the printed product can he controlled and regulated separately for each module.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a device for conveying printed products through a printing-related machine, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein: